Why does the music "break" in certain games?

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OneCrudeDude
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Why does the music "break" in certain games?

Post by OneCrudeDude » Mon Jul 27, 2015 7:52 pm

Basically, I've come to the attention that some games tend to have some issues with their sound systems. For an example, I was playing Elevator Action, and the game's melody got to the point where it wouldn't play unless I was in an elevator (triggering the triangle wave), or shooting/getting shot at (triggering the noise channel). If I did nothing, the game would be otherwise silent. Another example is the Famicom game B-Wings, it seems like the game will randomly change the duty cycle of the square waves, depending on what happens. This won't happen all the time, but it can and will happen by chance. I'm assuming that the game's internal logic has interfered with the audio logic, thus throwing out the whole system.

Alternatively, there is one game, Alpha Mission (also known as A.S.O: Armored Scrum Object in Japan) where the introductury jingle will play at a different speed each time you boot it up. Sometimes it will play fast, other times it will play slow. And there's another game, Rainbow Islands, where the triangle wave with literally screech and halt in a certain song after some time. But that appears to be more of a programming error than it is game interference.

Is it common for the music in NES games to be thrown out of whack under certain conditions?

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rainwarrior
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Re: Why does the music "break" in certain games?

Post by rainwarrior » Mon Jul 27, 2015 8:03 pm

Every game has bugs. Some of those bugs will affect music. This isn't specific to the NES.

tepples
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Re: Why does the music "break" in certain games?

Post by tepples » Mon Jul 27, 2015 8:13 pm

Case in point: In Tetris Blast for Game Boy (the North American version of BPS's Bombliss), one of the channels drops out of the music as soon as one line is cleared.

The title screen of Excitebike leaves the sweep register set, presumably from the last sound effect that was played. Similarly, Capcom games leave the sweep register set from whatever multicart menu or Game Genie ran first.

The track "Caverns of Cthulu" in Klax for NES fails to disable the triangle channel, leaving the previous song's triangle channel running behind it.

One of the StarTropics games has a similar problem to Rainbow Islands.
Last edited by tepples on Tue Jul 28, 2015 3:24 pm, edited 1 time in total.
Reason: added conjunction so as not to misidentify Excitebike's publisher

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dougeff
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Re: Why does the music "break" in certain games?

Post by dougeff » Tue Jul 28, 2015 2:08 pm

I disagree about Excitebike, tepples...

It was a Nintendo production, and I can't believe that they wouldn't have heard the sweep effect when testing the game.

Although, I removed the sweep effect (by modifying the original ROM) and it does sound better without it...
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Bregalad
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Re: Why does the music "break" in certain games?

Post by Bregalad » Tue Jul 28, 2015 2:22 pm

I belive he didn't say Excitebike was made by Capcom. He just made two separate statements about sweep registers, and regrouped them in the same line. Much like in:
Get a silk bag from the graveyard. Duck to live longer.

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Re: Why does the music "break" in certain games?

Post by NewRisingSun » Wed Jul 29, 2015 3:14 am

Which is a bad example, because it really is talking about a duck ;).

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Bregalad
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Re: Why does the music "break" in certain games?

Post by Bregalad » Wed Jul 29, 2015 5:36 am

Yes I knew but it's the only example I could come up where the ambitious is obvious. :)

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RushJet1
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Re: Why does the music "break" in certain games?

Post by RushJet1 » Sun Aug 30, 2015 10:43 am

dougeff wrote:I disagree about Excitebike, tepples...

It was a Nintendo production, and I can't believe that they wouldn't have heard the sweep effect when testing the game.

Although, I removed the sweep effect (by modifying the original ROM) and it does sound better without it...
You can also sit at the title screen of Excitebike and hit reset on your NES a few times, and this will play. Always thought that was funny.

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dougeff
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Re: Why does the music "break" in certain games?

Post by dougeff » Sun Aug 30, 2015 1:53 pm

Oh, yeah, you're right...

https://youtu.be/WqHgbnwHsjw
nesdoug.com -- blog/tutorial on programming for the NES

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Re: Why does the music "break" in certain games?

Post by Drag » Sun Aug 30, 2015 8:52 pm

tepples wrote:Case in point: In Tetris Blast for Game Boy (the North American version of BPS's Bombliss), one of the channels drops out of the music as soon as one line is cleared.
This is because the music engine has 6 tracks, each track is assigned a hardware channel to play on when initialized with data, and of course, the BGM uses 4 tracks. The blast sound effect actually uses 3 tracks, because they wanted the square channels to mute when a blast was going on. However, there's only 6 tracks, so one of the BGM tracks (the harmonizing square) gets overwritten by one of the tracks of the sound effect. I actually cooked up a patch to fix this if anyone's interested.

Spelunker for NES has a similar problem; the music engine only has 4 tracks, no special SFX tracks, so when a sound effect plays, that channel of the music gets overwritten until the music loops. The most noticable effect is that the noise channel drops out whenever you use the elevator, shoot, or a bomb explodes. The BGM doesn't use the second square, except for the jingle that plays when you advance to the next section of the mine, in which any sound effect that uses the square (jumping, for instance) overwrites the harmony track.

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Re: Why does the music "break" in certain games?

Post by tepples » Mon Aug 31, 2015 6:46 am

I guess I was fortunate in designing my music engine to have four music tracks and four dedicated sound effect tracks, one for each channel.

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Re: Why does the music "break" in certain games?

Post by Drag » Mon Aug 31, 2015 10:59 pm

That's how I always designed mine too, but I guess alternate solutions aren't bad to have too?

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